Several herbal medicines have been reported to exhibit stimulating effects on the immune system and are relatively nontoxic. This project was conducted to isolate and characterize the immunostimulating properties of polysaccharides (PSs) from Chinese plant medicines including (a) Astragali radix, (b) Cnidii rhizoma, (c) Angelicae radix, and (d) Hoelen. Polysaccharides were isolated by water extraction, 80% ethanol precipitation, Sephadex G-50 gel filtration and Sephadex DEAE A-50 chromatography. Molecular weights of PSs were shown as; Angelicae 61,000, Hoelen 21,000. Cnidii showed several small peaks while Astragali exhibited no peak in Sephadex G-150 column. Monosaccharide contents of PSs were identified by gas chromatography as follows: Angelicae -- Rha, Fuc, Ara, Xyl, Man, Glc, and Gal; Hoelen -- Fuc, Man, Glc, and Gal. The PSs obtained from Angelicae (B) and Hoelen showed high anticomplementary activity (16.8-22.8% of non-treated control). Furthermore, Hoelen PS exhibited cytokine inducing activity for production of interferon-r and TNF-a. Angelicae PS enhanced the pneumococcal PS-protein conjugate to produce more IL-6 in immune system.